Specify Connection Options指定连接选项

Connection Time Out Options连接超时选项

To specify the optional settings for your MongoClient, declare one or more available settings in the options object of the constructor as follows:要为MongoClient指定可选设置，请在构造函数的options对象中声明一个或多个可用设置，如下所示：

const client = new MongoClient(uri, {
  connectTimeoutMS: <integer value>,
  socketTimeoutMS: <integer value>
});

To see all the available settings, see the MongoClientOptions API Documentation.要查看所有可用的设置，请参阅MongoClientOptions API文档。

To specify maxTimeMS, pass in the maxTimeMS method as an option with a timeout specification to an operation that returns a Cursor:要指定maxTimeMS，请将maxTimeMS方法作为带有超时规范的选项传递给返回Cursor的操作：

const Cursor = collection.distinct('my-key', { maxTimeMS: 50 });

Close Sockets After Connection连接后关闭套接字

If you experience unexpected network behavior or if a MongoDB process fails with an error, you might not receive confirmation that the driver correctly closed the corresponding socket.如果您遇到意外的网络行为，或者MongoDB进程因错误而失败，您可能不会收到驱动程序正确关闭相应套接字的确认。

To make sure that the driver correctly closes the socket in these cases, set the socketTimeoutMS option. When a MongoDB process times out, the driver will close the socket. 为确保在这些情况下驱动程序正确关闭插座，请设置socketTimeoutMS选项。当MongoDB进程超时时，驱动程序将关闭套接字。We recommend that you select a value for socketTimeoutMS that is two to three times longer than the expected duration of the slowest operation that your application executes.我们建议您为socketTimeoutMS选择一个值，该值比应用程序执行的最慢操作的预期持续时间长两到三倍。

Prevent Long-Running Operations From Slowing Down the Server防止长时间运行的操作减慢服务器速度

You can prevent long-running operations from slowing down the server by specifying a timeout value. You can chain the maxTimeMS() method to an operation that returns a Cursor to set a timeout on a specific action.您可以通过指定超时值来防止长时间运行的操作减慢服务器的速度。您可以将maxTimeMS()方法链接到一个操作，该操作返回一个游标以设置特定操作的超时。

The following example shows how you can chain the maxTimeMS() method to an operation that returns a Cursor:以下示例显示了如何将maxTimeMS()方法链接到返回Cursor的操作：

// Execute a find command执行查找命令
await collection
  .find({ $where: "sleep(100) || true" })
  .maxTimeMS(50);

keepAlive Connection OptionkeepAlive连接选项

The keepAlive connection option specifies whether to enable Transmission Control Protocol (TCP) keepalives on a TCP socket. keepAlive连接选项指定是否在TCP套接字上启用传输控制协议（TCP）保活。If you enable keepalives, the driver checks whether the connection is active by sending periodic pings to your MongoDB deployment. This functionality works only if your operating system supports the SO_KEEPALIVE socket option.如果启用keepalives，驱动程序会通过向MongoDB部署发送定期ping来检查连接是否处于活动状态。仅当您的操作系统支持SO_KEEPALIVE套接字选项时，此功能才有效。

The keepAliveInitialDelay option specifies the number of milliseconds that the driver waits before initiating a keepalive.keepAliveInitialDelay选项指定驱动程序在启动保活之前等待的毫秒数。

The 5.3 driver version release deprecated these options. Starting in version 6.0 of the driver, the keepAlive option is permanently set to true, and the keepAliveInitialDelay is set to 300000 milliseconds (300 seconds).5.3驱动程序版本已弃用这些选项。从驱动程序的6.0版本开始，keepAlive选项永久设置为true，keepAliveInitialDelay设置为300000毫秒（300秒）。

Additional Information附加信息

To learn more about connection options that you can set within a MongoClientOptions instance, see MongoClientOptions in the API Documentation.要了解有关可以在MongoClientOptions实例中设置的连接选项的更多信息，请参阅API文档中的MongoClientOptions。